Optical fibers are used in fiber-optic communications to permit high bandwidth transmission of information over longer distances. The optical fiber is a cylindrical dielectric waveguide that transmits light along its axis, by the process of total internal reflection. As shown in FIG. 1, polarization maintaining optical fiber conventionally includes a transparent core 105 surrounded by a transparent cladding layer 104, which has a lower index of refraction compared to the transparent core 105 and also stress rods 106 or other stress inducing elements. FIG. 1 further illustrates the cross-sectional views of various optical fibers, such as the Panda fiber 101, the elliptical-clad fiber 102, and the bow-tie fiber 103.
Due to some of these unique characteristics of optical fibers, joining lengths of optical fiber using an interconnect is more complex than joining electrical wire or cable. Optical fibers may be connected to each other by connectors or by splicing. Splicing occurs when two fibers are joined together to form a continuous optical waveguide. Alternatively, an optical fiber connector terminates the end of an optical fiber, and enables quicker connection and disconnection than splicing. The connectors mechanically couple and align the cores of fibers so that light can pass from one core to the next.
Optical signals traveling in optical fiber frequently are coupled to optoelectronic circuits. There are a variety of known techniques and devices for coupling optical fibers to optoelectronic circuits. Once an optical signal is coupled to an optoelectronic circuit, the signal can be processed either as an optical signal or converted to an electronic signal for further processing.
The flat end of an optical fiber can be directly connected to the edge of an integrated circuit. Consequently, an optical signal can be coupled to a flat end of an integrated waveguide, but the fiber and the waveguide can have different cross sectional geometries and can be different in size.
FIG. 2 illustrates an example of an arrangement of coupling a fiber to a source (e.g., a laser). A feed fiber (optical fiber 206) is inserted inside a metallic jacket or lensed capsule 202, through a metal wall or source alignment module 203 of the package 200. The feed fiber 206 can be adjusted along the Cartesian axis in three dimensions, to enable the core of the fiber to axially align to the waveguide of the source 204 in order to correctly capture the light 205 from the source 204.
Embodiments of the invention disclose an optical package interconnect that maintains polarization regardless of orientation and optical fiber length. Therefore, the interconnect does not require manual adjustment when connecting fiber optic systems.